1. Field of the Invention
The present invention relates to a cooling structure for an electronic circuit unit in which the electronic circuit unit, including, for example, a printed-circuit board, is arranged horizontally, and cooling air for the electronic circuit unit is forced to flow in the horizontal direction. This cooling structure may be applied to various information processing devices, communication devices, and other electronic devices.
2. Description of the Related Art
FIGS. 1A and 1B schematically show a communication device subunit 1 (i.e., a subunit 1 of the communication device) with FIG. 1A being a front view and FIG. 1B being a plan view. In FIG. 1A, first electronic circuit units 2, including printed-circuit boards, are attached to a frame from the front side. The first electronic circuit units 2 are horizontally disposed. Six layers of the first electronic circuit units 2 are individually attached such that these six electronic circuit units 2 are attachable to and detachable from the frame. Two power units 3 are inserted at the right and left sides below the first electronic circuit units 2.
A back board 4, also including a printed-circuit board, is indicated by the dashed line around the center of FIG. 1B, and extends in a vertical direction. This back board 4 has connectors which are connected to back side connectors (not shown) of the first electronic circuit units 2 by plug connections. The back board 4 is connected to the power units 3 by plug connections.
A plurality of second electronic circuit units 5 similar to the first electronic units 2 are attachably and detachably mounted at the back side opposite the front side. The second electronic circuit units 5 are horizontally disposed. These second electronic circuit units 5 are connected to the back board 4 by plug connectors.
At the left side of FIG. 1B, a first fan unit 6 is inserted toward one side of the back board 4 from the front side of the subunit 1, and a second fan unit 7 is inserted toward the other side of the back board 4 from the back side of the subunit 1. The first and second fan units 6 and 7 are also connected to the back board 4 by plug connectors. At the right side of FIG. 1B, a wide air filter 8 is inserted from the front side of the subunit 1, and extends substantially over a range where the first electronic circuit units 2 and the second electronic circuit units 5 are positioned.
Panel boards are provided to cover exposed sides of the first electronic circuit units 2, the second electronic circuit units 5, the power units 3, the first fan unit 6, the second fan unit 7, and the air filter 8. The panel boards are fixed to the frame by means of attaching screws. In this manner, the front side and back side of the communication device subunit 1 are closed by the respective panel boards without an opening to the outside.
Fitting metals 9 which are L-shaped in FIG. 1B are attached at the right and left sides of the front side, as shown in FIG. 1A. The communication device subunit 1 is attached to a rack (which will be described later) by attaching holes 11 of the attaching metals 9. FIG. 2 is a side view showing the left side of FIGS. 1A and 1B. The first fan unit 6 has nine fans 12, and the second fan unit 7 has six fans 13.
Although an upper surface and both side surfaces are covered by a cover 14, many air holes for air passage are provided on the both side surfaces over a wide range. Electric circuits and signal circuits are connected between the respective internal units via the back board 4. The internal units may be connected to electric circuits and signal circuits used for connection with external devices or the like by using connectors (not shown). Electronic components which operate at a high speed are disposed in high density on the first electronic circuit units 2 and the second electronic circuit units 5. Accordingly, when the first and second electronic circuit units 2 and 5 operate, considerable heat is generated. For this reason, the first fan unit 6 and the second fan unit 7 are actuated in order to discharge the heated air to the outside of the left side of the communication device subunit 1 in FIG. 1B via the air holes formed on the cover 14. Cool air of the outside is introduced from the right side of FIG. 1B via air holes formed on the cover 14 and the air filter 8.
The introduced air passes by the arranged circuit boards of the first and second electronic circuit units 2 and 5, absorbs the heat generated from the electronic components, and is discharged to the outside by the first and second fan units 6 and 7. Thus, the electronic components are cooled. The power units 3 are cooled by the first fan unit 6 in the same manner.
FIG. 3 is a cross sectional view of the rack which accommodates the communication device subunits 1. In FIG. 3, the lower side is the front side of the rack, and the upper side is the back side of the rack. As a basic structure, this rack 21 includes a pair of longitudinal frames 22 and a pair of longitudinal frames 23, a ceiling member 24, and a bottom sheet member shown in FIG. 4. The pair of the longitudinal frames 22 are provided at the front side of the rack 21, and the pair of the longitudinal frames 23 are provided at the back side of the rack 21. The longitudinal frames 22 and 23 are made of sheet metal, and are formed by folding the sheet metal. The ceiling member 24 and the bottom sheet member 25 are coupled to the longitudinal frames 22 and 23 at the upper side and the bottom side, respectively.
In FIG. 3, reinforcing members for coupling the longitudinal frames 22 and 23 with each other, various members of the bottom sheet member 25, and attaching screws are omitted for the sake of the simple illustration. These members are also omitted in other drawings. In the rack 21, side covers 26 on both sides, and a back side boor 27 on the back side which can be opened and closed are provided, but are not necessary in some cases. When the side covers 26 and the back side door 27 are provided, appropriate air holes are formed in them for the reason which will be described later.
Pairs of guide supporting members 28 or rails are attached at front end surfaces and back end surfaces of the longitudinal frames 22 and 23 inside the rack 21. The rails 28 are attached at predetermined intervals in a vertical disposition such that a pair of rails 28 are symmetrical with respect to the right and left sides. The rails 28 are used for guiding the communication device subunit 1 when the communication sub unit 1 is inserted into the rack 21. FIG. 4 is a front view of the rack 21 into which the communication device subunits 1 have been inserted. The communication device subunit 1 is placed on the rails 28, and inserted into the rack 21. The communication device subunit 1 is then fixed to the front surfaces of the longitudinal frames 22 at the front side of the rack 21, by applying screws to attaching holes 11 of the attaching metals 9. The state in which the communication device subunits 1 have been attached in this manner is shown in FIG. 4.
Appropriate spaces are provided between the communication device subunits 1. Furthermore, an appropriate space is provided at the upper side of the top most communication device subunit 1, and an appropriate space is also provided at the lower side of the bottom most communication device subunit 1. In order to close these spaces, panel boards 29 whose vertical width are narrow are attached to the rack 21 by means of screws, as shown in FIG. 4. In addition, a strong base frame 31 is provided at the bottom of the rack 21 for supporting the entire rack 21, and firmly stabilizing (or fixing by means of screws) the rack 21 on a floor or the like. FIG. 5 is a cross sectional view of the rack 21 shown in FIG. 4, and shows an upper surface of one of the communication subunits 1.
FIG. 6 is a cross sectional view of the rack 21 which is the same as that of FIG. 5, but shows cooling air flow, indicated by arrows, to the communication device subunit 1 shown in FIGS. 1A and 1B together with the rack 21. As apparent from FIG. 6, the communication device subunit 1 is set such that the back part of the communication subunit 1 does not overlap the longitudinal frames 23 at the back side of the rack 21. This is so that electric wiring cables are not located where discharge air, generated by the first fan unit 6 and the second fan unit 7, flows in order not to block the discharge and/or intake air which flows between both sides of the rack 21 in a horizontal and/or vertical direction. The same arrangement is applied to the air intake side so that the electric wiring cables or the like may not obstruct the air filter 8. Accordingly, there is no obstacle in that air is taken in from the outside at one side of the rack 21, and the air is discharged to the outside at the other side of the rack 21, as indicated by the arrows.
When necessary, for example, for a large volume of a communication amount, the rack 12 can accommodate a plurality of communication device subunits 1, and a plurality of racks, each of which includes these communication device subunits 1, are arranged in a row and/or in a parallel manner. As described above by referring to FIG. 6, the rack 21 takes in air for cooling from one side, and discharges the heated air from the other side. Accordingly, where a plurality of racks 21 are arranged in a row, it is required that an appropriate space should be provided between the racks 21, as shown in FIG. 7.
A sufficient distance between the racks 21 is needed so that the discharged heated air may be sufficiently dispersed, and the temperature of the air that the adjacent rack 21 takes in is low enough so as not to have an adverse effect on cooling of the adjacent communication device subunit 1. If an appropriate space between the racks 21 is not to be provided, an appropriate wall such as a partition board should be provided between the racks 21. However, this creates a problem that the discharged air flows into the air intake side via another air path.
When the racks 21 are arranged such that the racks 21 are close to each other as shown in FIG. 8, a side cover 32 which has no air holes and prevents interference with the air of the outside is provided. However, in the case of this structure, the discharge air mixes with the intake air by circulating in the spaces at the back side of the communication device subunits 1 and the spaces between the communication device subunits 1. The resulting temperature of the inside is raised, so this structure cannot be implemented.
With the view of the above-mentioned structure, it is an object of the present invention to provide a cooling structure for an electronic circuit unit in which the above-mentioned problems do not occur, cooling air for the electronic circuit unit which is forced to flow in a horizontal direction is effectively separated such that discharge air is not mixed with intake air.
According to a first aspect of the present invention, there is provided a cooling structure for an electronic circuit unit in which cooling air passes the electronic circuit unit of the subunit in a horizontal direction. Specifically, this cooling structure includes separation members provided at the upper side and/or the lower side of the subunit for separating cooling intake air and discharge air into a front area and a back area. These separation members extend from one side to the other side of the subunit.
With this cooling structure, the cooling air is introduced from one side of the subunit and discharged from the other side of the subunit in order to cool the electronic circuit unit of the subunit. The intake air introduced from one side of the subunit is separated from the discharge air discharged from the other side of the rack by the separation member provided at the upper side and/or the lower side of the subunit. The discharge air is guided toward the discharge side by the separation member. In this manner, the intake air is not mixed with the discharge air.
According to a second aspect of the present invention, there is provided a cooling structure for a horizontally disposed electronic circuit unit in which cooling air passes the electronic circuit unit of the subunit in a horizontal direction. Specifically, this cooling structure includes separation members provided at the upper side and/or the lower side of the subunit for separating cooling intake air and discharge air into a front area and a back area. These separation members extend from one side to the other side of the subunit.
With this cooling structure, the cooling air is introduced from one side of the subunit and discharged from the other side of the subunit to cool the horizontally disposed electronic circuit unit. The intake air introduced from one side of the subunit is separated from the discharge air discharged from the other side of the rack by the separation member provided at the upper side and/or the lower side of the subunit. The discharge air is guided toward the discharge side by the separation member. In this manner, the intake air is not mixed with the discharge air.
According to a third aspect of the present invention, there is provided a cooling structure for an electronic circuit unit in which cooling air is forced to pass by the electronic circuit unit in a horizontal direction. Specifically, this cooling structure includes separation members provided at an upper side and/or a lower side of the subunit for separating intake air and discharge air of the cooling air into a front area and a back area. The separation member extends from one side to the other side of the subunit. Particularly, this cooling structure further includes a shielding member provided on the separation member and extending toward the side surface of the rack which accommodates the subunit. The shielding member shuts off upward and downward air flow of the cooling air.
With this cooling structure, the cooling air is introduced from one side of the subunit and discharged from the other side of the subunit to cool the electronic circuit unit of the subunit. The intake air introduced from one side of the subunit is separated from the discharge air discharged from the other side of the rack by the separation member provided at the upper side and/or the lower side of the subunit. The discharge air is guided toward the discharge side by the separation member. In this manner, the intake air is not mixed with the discharge air. The discharge air is also prevented from flowing toward the air intake side via the spaces of the upper side and the lower side of the subunit, by the shutting effect of the shielding member.
According to a fourth aspect of the present invention, the electronic circuit unit in the cooling structure of any one of the first, second, and third aspects of the present invention includes a printed-circuit board. According to a fifth aspect of the present invention, the cooling air in the cooling structure of the electronic circuit unit in any one of the first, second, and third aspects of the present invention is caused to pass by the electronic circuit unit by a fan which is provided at a side surface of the electronic circuit unit and which is operated by electric power.
According to a sixth aspect of the present invention, the separation member includes an upper surface sheet, a lower surface sheet, and a hypotenuse portion which is provided between the upper surface sheet and the lower surface sheet and extends from one side at a front side to the other side at a back side so as to shut off air flow between the front area and the back area.
According to a seventh aspect of the present invention, the separation member includes an upper surface sheet, a lower surface sheet, and a shielding sheet which is provided between the upper surface sheet and the lower surface sheet, extends from one side at a front side to the other side at a back side, has at least three bent points so at to separate the intake air and discharge air into the front area and the back area, and shut off air flow between the front area and the back area, with the front area being a right area and the back area being a left area.
According to an eighth aspect of the present invention, the cooling structure further includes a shielding member for shutting off upward and/or downward flow of the cooling air, wherein the shielding member extends toward a side surface of a rack which accommodates the subunit, and the shielding member is disposed on a rail which is provided in the rack and on which the subunit is inserted and which supports the subunit.
According to a ninth aspect of the present invention, the shielding member is integrally formed on an upper surface sheet or a lower surface sheet of the separation member.
Other objects, features, and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings.